Super absorbent polymers (SAPs) are synthetic polymeric materials having a function capable of absorbing water about five hundred to one thousand times its own weight, and started to be practically used as sanitary equipments. Now, the super absorbent polymers have been widely used as materials for soil water retaining agent for gardening, civil engineering, building packing materials, seedling sheets, freshness preservatives in food distribution fields, fomentation, etc., in addition to hygienic goods such as paper diapers for children, etc.
In addition, as a ratio of the super absorbent polymer (SAP)/core of the diaper is increased, and the diaper becomes thin, an importance of permeability (GBP: gel bed permeability) enabling efficient diffusion of urine by the super absorbent polymer on behalf of a pulp is on the rise.
When the permeability is poor, the urine is not evenly spread in the core of the diaper, and a spread area is also decreased. Even though centrifugal retention capacity (CRC) and absorption under load (AUL) of the super absorbent polymer are high, if the urine is not well spread, many areas of the diaper may not be used, and performance of the diaper is also deteriorated.
Regarding this, various factors capable of explaining high permeability have been introduced according to the related art. As representative examples, technologies of treating a surface with silica which is a particulate or adding a polyvalent metal salt are disclosed. However, development of a super absorbent polymer simultaneously satisfying both of improvement of porosity of the super absorbent polymer and securement of excellent permeability has been demanded.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.